Large sulfur-isotope anomaly in nonvolcanic sulfate aerosol and its implications for the Archean atmosphere

Shaheen, R.; Abaunza, Mariana; Jackson, Teresa L.; McCabe, J. R.; Savarino, Joël; Thiemens, M. H.

doi:10.1073/pnas.1406315111

Cited by 41 publications

(93 citation statements)

References 46 publications

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“…3). Shaheen et al (21) distinguished different sources of modern sulfate aerosols based on concentrations and δ 34 S values of SO 4 in ice-core horizons. The low and intermediate δ 34 S ranges (δ 34 S = 1.4-2.6‰ and +12 ± 1.4‰) have been attributed to combining photoexcitation and photodissociation processes affecting different sulfur sources (mainly SO 2 and OCS) in the stratosphere.…”

Section: Discussionmentioning

confidence: 99%

“…The low solubility and long atmospheric lifetime with respect to tropospheric chemistry and photolysis enable a significant fraction of OCS to reach the stratosphere (42), where it photo-dissociates to carbon monoxide and elemental sulfur (S 0 ) on UV irradiation in the 200-to 260-nm range. The sulfur atom is oxidized by different pathways (OH/H 2 O 2 /CO 2 /O 3 /O 2 ) to SO 2 and ultimately sulfate, which is thought to contribute to the stratospheric sulfate aerosol layer (21,43). Laboratory experiments have shown that OCS photolysis at short wavelengths does not produce 33 S-isotope anomaly in oxygen-free conditions but negative Δ 36 S down to −1.5‰ (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…The presence of S-MIF in the present-day atmosphere in nonvolcanic aerosols after the super ENSO 1997-1998 event has led Shaheen et al (21) to suggest that both SO 2 and OCS sources could have contributed to sulfur-isotopic anomalies in the Archean. Our results fully support this hypothesis.…”

Section: Discussionmentioning

confidence: 99%

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Multiple sulfur-isotope signatures in Archean sulfates and their implications for the chemistry and dynamics of the early atmosphere

Muller

Philippot

Rollion‐Bard

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Sulfur isotopic anomalies (Δ 33 S and Δ 36 S) have been used to trace the redox evolution of the Precambrian atmosphere and to document the photochemistry and transport properties of the modern atmosphere. Recently, it was shown that modern sulfate aerosols formed in an oxidizing atmosphere can display important isotopic anomalies, thus questioning the significance of Archean sulfate deposits. Here, we performed in situ 4S-isotope measurements of 3.2-and 3.5-billion-year (Ga)-old sulfates. This in situ approach allows us to investigate the diversity of Archean sulfate texture and mineralogy with unprecedented resolution and from then on to deconvolute the ocean and atmosphere Archean sulfur cycle. A striking feature of our data is a bimodal distribution of δ 34 S values at ∼+5‰ and +9‰, which is matched by modern sulfate aerosols. The peak at +5‰ represents barite of different ages and host-rock lithology showing a wide range of Δ 33 S between −1.77‰ and +0.24‰. These barites are interpreted as primary volcanic emissions formed by SO 2 photochemical processes with variable contribution of carbonyl sulfide (OCS) shielding in an evolving volcanic plume. The δ 34 S peak at +9‰ is associated with non-33 S-anomalous barites displaying negative Δ 36 S values, which are best interpreted as volcanic sulfate aerosols formed from OCS photolysis. Our findings confirm the occurrence of a volcanic photochemical pathway specific to the early reduced atmosphere but identify variability within the Archean sulfate isotope record that suggests persistence throughout Earth history of photochemical reactions characteristic of the present-day stratosphere.Archean | sulfate | sulfur isotopes | atmosphere photochemistry T he amount of sulfate and its sulfur isotopic composition in the ocean through time is a function of the dynamic changes of sulfate sources (oxidative weathering on land, magmatic and hydrothermal input, and atmospheric photochemical reactions) and sulfate sinks (microbial and hydrothermal sulfate reduction and sulfate mineral precipitation). Although the Earth's sulfate budget can be reasonably well constrained after ∼2.3 billion years (Ga) ago, when free oxygen became a permanent component of the atmosphere, our understanding of the ocean sulfate budget before 2.3 Ga ago is subject to uncertainties. The occurrence of mass-independent sulfur-isotope anomalies (MIF-S, noted Δ 33 S and Δ 36 S) in sedimentary sulfur (sulfide and sulfate) of Archean age (1) and the photochemical models (2) for the production and preservation of these anomalies support the view that the Archean atmospheric O 2 concentration was lower than 10 −5 times the present atmospheric level. In this model, photochemical reactions involving volcanic SO 2 in the anoxic atmosphere yields both a reduced sulfur reservoir that can carry a highly positive Δ 33 S and an oxidized sulfur reservoir with modestly negative Δ 33 S, the Δ 36 S values being of opposite sign. The corollary to this model is that sulfate influx from oxidative weathering on land should...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Multiple sulfur-isotope signatures in Archean sulfates and their implications for the chemistry and dynamics of the early atmosphere

Muller

Philippot

Rollion‐Bard

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…[163] In high-resolution sulfur isotope records from polar regions,aconsistent pattern is that D 33 S values change from positive to negative during deposition while D 36 Sv alues changes in reverse fashion (negative to positive). Am ass balance of isotopic anomalies (i.e., average D 33 Sa nd D 36 Sv alues equal to zero) in as ingle stratospheric volcanic event can be hardly reached in observation [117,159,160] because ap ortion of sulfate aerosols formed in the stratosphere may deposit during transport, leading to ah ighly spatially heterogeneous mass independent sulfur isotopic signature in the stratosphere as shown in an early twodimensional model. This temporal evolution of sulfur isotopic anomalies highlights mass independent sulfur isotope effects of SO 2 photolytic reactions and sulfate production and their differential atmospheric behaviors during polar transport (e.g.,different transport speed and deposition lifetime).…”

Section: Present-day Sulfur Isotopic Anomaliesmentioning

confidence: 99%

Use of Isotope Effects To Understand the Present and Past of the Atmosphere and Climate and Track the Origin of Life

Thiemens

Lin

2019

Angew Chem Int Ed

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Stable isotope ratio measurements have been used as a measure of a wide variety of processes, including solar system evolution, geological formational temperatures, tracking of atmospheric gas and aerosol chemical transformation, and is the only means by which past global temperatures may be determined over long time scales. Conventionally, isotope effects derive from differences of isotopically substituted molecules in isotope vibrational energy, bond strength, velocity, gravity, and evaporation/condensation. The variations in isotope ratio, such as 18O/16O (δ18O) and 17O/16O (δ17O) are dependent upon mass differences with δ17O/δ18O=0.5, due to the relative mass differences (1 amu vs. 2 amu). Relations that do not follow this are termed mass independent and are the focus of this Minireview. In chemical reactions such as ozone formation, a δ17O/δ18O=1 is observed. Physical chemical models capture most parameters but differ in basic approach and are reviewed. The mass independent effect is observed in atmospheric species and used to track their chemistry at the modern and ancient Earth, Mars, and the early solar system (meteorites).

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“…2) thus suggest that the atmospheric signal has been little modified by biological activity after deposition and rather indicates that microbial S cycling, if it was present at all, was not a significant component of the Nuvvuagittuq sedimentary environment (10,44). If a shared biogenic control on the S-MIF record at both the beginning and the end of the Archean Eon is unlikely, recurrent gas inputs in the atmosphere by magmatic activity may be able to produce comparable photochemical pathways at any time in the Archean (45)(46)(47). Such a strong geological control on S-MIF record would then be decoupled from singular events like the emergence of biogenically dominated element cycling or intense bombardments by meteorites.…”

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confidence: 99%

Atmospheric record in the Hadean Eon from multiple sulfur isotope measurements in Nuvvuagittuq Greenstone Belt (Nunavik, Quebec)

Thomassot

O’Neil

Francis³

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Mass-independent fractionation of sulfur isotopes (S-MIF) results from photochemical reactions involving short-wavelength UV light. The presence of these anomalies in Archean sediments [(4–2.5 billion years ago, (Ga)] implies that the early atmosphere was free of the appropriate UV absorbers, of which ozone is the most important in the modern atmosphere. Consequently, S-MIF is considered some of the strongest evidence for the lack of free atmospheric oxygen before 2.4 Ga. Although temporal variations in the S-MIF record are thought to depend on changes in the abundances of gas and aerosol species, our limited understanding of photochemical mechanisms complicates interpretation of the S-MIF record in terms of atmospheric composition. Multiple sulfur isotope compositions (δ33S, δ34S, and δ36S) of the >3.8 billion-year-old Nuvvuagittuq Greenstone Belt (Ungava peninsula) have been investigated to track the early origins of S-MIF. Anomalous S-isotope compositions (Δ33S up to +2.2‰) confirm a sedimentary origin of sulfide-bearing banded iron and silica-rich formations. Sharp isotopic transitions across sedimentary/igneous lithological boundaries indicate that primary surficial S-isotope compositions have been preserved despite a complicated metamorphic history. Furthermore, Nuvvuagittuq metasediments recorded coupled variations in 33S/32S, 34S/32S, and 36S/32S that are statistically indistinguishable from those identified several times later in the Archean. The recurrence of the same S-isotope pattern at both ends of the Archean Eon is unexpected, given the complex atmospheric, geological, and biological pathways involved in producing and preserving this fractionation. It implies that, within 0.8 billion years of Earth’s formation, a common mechanism for S-MIF production was established in the atmosphere.

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Large sulfur-isotope anomaly in nonvolcanic sulfate aerosol and its implications for the Archean atmosphere

Cited by 41 publications

References 46 publications

Multiple sulfur-isotope signatures in Archean sulfates and their implications for the chemistry and dynamics of the early atmosphere

Multiple sulfur-isotope signatures in Archean sulfates and their implications for the chemistry and dynamics of the early atmosphere

Use of Isotope Effects To Understand the Present and Past of the Atmosphere and Climate and Track the Origin of Life

Atmospheric record in the Hadean Eon from multiple sulfur isotope measurements in Nuvvuagittuq Greenstone Belt (Nunavik, Quebec)

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